Spark plug shield



June 13, 1939. H, RABEzzANA SPARK PLUG SHIELD Filed Feb. 24, 1936 Wmv? Qabzzafzcz gmc/who@ Patented June 13,

PATENT oFFlcE 2,162,118 SPA PLUG SHIELD Hector Ra eral Motors poration of Delaware Flint, Mich., amignor to Ge rporation,

n- Detroit, Mich., a cor- Application February 24, 1936, Serial No. 05,208

My invention relates to spark plugs for internal combustion engines and particularly to shielding means for preventing the radiation of high tension current from the spark plug proper. thus reducing or eliminating the interference which its operation produces on nearby sending or receiving radio sets and analogous sensitive apparatus located adJacent to the engine. My shielding means is so designed and arranged that it will reduce the flow of heat upward from the metallic shell of the spark plug, which is positioned in good heat conducting relation to the engine cyldissipates some of the heat inder. The type of shielding means referred to in this invention was broadly disclosed in the pending Peters and Astin patent application S. N. 37,176 and filed August 21, 1935. It is in the form of a metallic cage surrounding the portion of the spark plu'g projecting from the top of the shell and is an upward continuation of said shell. It ls also providedv to receive the ignition cable shielding, thus cooperating in accomplishing complete shielding of the ignition system.

My shield isin the form of a hollow member comprised of a lower portion or spark plug shell, an upper portion or ring, and an intermediate portion comprising a plurality of longitudinal bars preferably separated each from the other by a space having substantially the same width as the bars themselves.

These bars or strips may be secured to the spark plug shell in any suitable manner such as by welding, brazing, soldering. etc. 'I'he number of bars used depends somewhat upon the particular conditions of operation to which thespark plug is to be subjected. The spaces between the bars permit some air circulation which desirably from the spark plug.

The lobject of nu invention is to provide for improved shields of the type under consideration, which 'are of simple and sturdy wnstruction, thus simplifying their manufact lowering the cost and ,at the same time mainhrimnl the shield efficiency requirements.

Other advantages such as pleasing appearance and compactness will be evident from the follow- I ing description and dra The preferred forms of my invention are illustrated in the `aoco drawing, and the particular features thereof an Dlrtlmlarlr pointed out, in the concluding claims.

In the drawing:

l'igurelisasectionshowingasparkplughaving a shield made in accordance with my invention.

'of longer life for use on' radio equipped 4 Claims.D (Cl. 123-169) of the upper end of the shield in perspective. elevation of another form of Figure 2 is a view shown in Figure 1 Figure 3 is an built-up shield.

Figure 41s a section upon the line 4 4, Figure 3.

In Figures 1 and 2 there is shown a shield built up on the shell I5. In this design the shield is formed by a number of substantially, equally spaced rods I6 made preferably of poor heat conducting material, such as stainless steel, and which are held in place by being press-iltted at their extremities into holes provided in the shell 35 and the upper internally threaded ring Il as shown.y These rods or bars are more securely fastened to said parts 35 and I1 by a soldering, brazing or welding operation, if desired.

In Figures 3 and 4 there is shown another form of built-up shield, I8 and 39 designate the usual shell and internally threaded ring respectively. These two parts are connected by a plurality of at bars 40 which are so positioned that the major faces thereof lie at an acute angle to the radius of the shield. In this position the bars deflect air into the shield and cause a desirably more rapid ow of air over the Vspark plug while functioning in actual service.

The bars 40, which are made fol' rather poor heat conducting material, are heldin place by being press-tted at their extremities into slots properly machined into shell "and ring I9, as shown. In order to obtain a more secure fastening and a more intimate contact between these related parts, they may be brazed, welded or soldered together at their points of contact.

Both above mentioned forms of shields are substantially of the same shielding value, and will adequately shield the spark plug proper against radio interferences caused by its operation. Besides, these shields permit an eiilcient air circulation around the upper assembly oi' the spark plug, thus reducing not only the heat transmitted to a very eicient plug y motor cars, boats and especially aircraft.

Having thus described and explained my invention I claim and desire to secure by Letters Patent:

1. In electrical shielding means forl a spark Plug and in combination with a ,base having an y threaded lower portion, and a passage extending longltudinally thereof and the upper md of which is interiorly threaded;

extending' between,

rectangular cross section positioned so that the 2 a internally threaded ring spaced apart from said base; and a plurality of circumferen vily spaced bars separate and independent of one another andthe endsl oi which are secured within openings provided in, said base portion and said ring. f 2. An electrically shielding member for a spark plug, comprising a hollow me ber having upper and lower portions and an intermediate portion, said `intermediate portion comprising a plurality of spaced apart longitudinally extending bars o! major faces thereof are at an acute angleto the radius of the shield; said bars being` separate and independent of one another and the upper and lower ends thereof being securely and electrically connected to said upper and lower portions by brazing, soldering or welding.

3. The invention defined by claim 2, said bars being made oi a material having a low heat conductivity. l

4. The invention denedby claim 2, the ends of said bars being secured in slots formed in the 10 faces doi said upper and lower portions.

` HECTOR RABEzzANA. 

